1. Field of the Invention
The present invention is related to a reflector, a liquid crystal display device, and an indenter used for manufacturing a reflector. More particularly, the present invention is related to a reflector having a good reflection characteristic as viewed in two directions, to a liquid crystal display device having the reflector, and to an indenter suitable for manufacturing the reflector.
2. Description of the Related Art
A reflective liquid crystal display device uses sunlight or illumination light emitted from, for example, a front light as a light source, and is generally used for a portable information terminal required to have low power consumption. In addition, a transflective liquid crystal display device, which is another type of liquid crystal display device, is operated in a transmissive mode in which a backlight is turned on when the amount of external light is insufficient, and is operated in a reflective mode in which the backlight is turned off when the amount of external light is sufficient. The transflective liquid crystal display device is generally used for portable electronic apparatuses, such as a cellular phone and a notebook-type personal computer. The reflective liquid crystal display device or the transflective liquid crystal display device is provided with a reflector which reflects external light and light emitted from the front light, or which reflects external light and transmits light emitted from the backlight. For example, a reflector according to the related art has been disclosed in Japanese Unexamined Patent Application Publication No. 2002-82213.
FIG. 29 is a perspective view showing the reflector disclosed in Japanese Unexamined Patent Application Publication No. 2002-82213. As shown in FIG. 29, a reflector 730 includes a plate-shaped substrate 728 and a plurality of reflective concave portions 728b that are provided on a surface S of the substrate 728 so as to be adjacent to each other. In addition, a reflective film 728a composed of, for example, an Al film is formed on the substrate 728. FIG. 30A is a plan view showing the concave portion 728b. As shown in FIG. 30A, the concave portion 728b is defined by an outline composed of a first curved line 728c positioned on one circumferential side S1 and a second curved line 728d positioned on the other circumferential side S2, and the first curved line 728c is divided from the second curved line 728d by a boundary line E. The outline of the concave portion 728 has an asymmetric shape with respect to the line XXXB-XXXB of FIG. 30A in plan view. That is, a section corresponding to the line XXXB-XXXB is a symmetric surface of the concave portion.
Further, FIG. 30B is a cross-sectional view of the concave portion 728b taken along the line XXXB-XXXB of FIG. 30A. As shown in FIG. 30B, in the concave portion 728b, the first curved line 728c extends from the one circumferential side S1 to the boundary line E through a lowest point D, and the second curved line 728d is continuously linked to the first curved line so as to extend from the boundary line E to the other circumferential side S2. As such, the sectional shape of the concave portion 728b is asymmetric with respect to the lowest point D.
Furthermore, as described above, in the reflector 730, the plurality of concave portions 728b are provided on the substrate 728 so as to be adjacent to each other. In this case, the concave portions 728b are regularly arranged such that their lines XXXB-XXXB shown in FIG. 30A are arrayed in the same direction.
From the viewpoint of the relationship between a reflection angle and reflectance, the reflection characteristic profile of the reflector 730 does not show a Gaussian distribution having the peak of reflectance at a specular reflection angle, but shows a substantially trapezoidal profile in which high reflectance is obtained in a wide reflectance angle range. That is, light incident on the reflector in a direction is mainly diffused and reflected from the concave portions 728b of the reflector 730, which causes high reflectance to be obtained in a wide angle range. This diffused reflection is caused by the sectional shape of the concave portion 728b. 
When the reflector 730 is applied to a liquid crystal display device serving as a display unit of, for example, a cellular phone, it is preferable to arrange the reflector such that a region where high reflectance is obtained is arranged in the viewing direction of an operator, considering the viewing direction of the operator with respect to the display unit of the cellular phone.
In recent years, cellular phones having a digital camera incorporated therein have come into widespread use. When taking a photograph using the incorporated digital camera, an operator uses a display unit of the cellular phone as a finder. In addition, when viewing the photographed images, the operator uses the display unit as a display screen. Further, the display unit of the cellular phone generally has a longitudinal shape. Therefore, when photographing a person, the operator takes a picture with the display unit positioned in the longitudinal direction. When photographing a landscape, the operator takes a picture with the display unit positioned in the widthwise direction. As such, in recent years, there has been an increasing tendency for the operator to view the display unit of the cellular phone in two directions, that is, the longitudinal direction and the widthwise direction.
As described above, the reflector provided in the liquid crystal display device according to the related art is designed to show the optimum reflection characteristic profile, as viewed in one direction. However, in the related art, it is not considered that the liquid crystal display device is viewed in two directions. Therefore, in this case, when the display unit is viewed in the longitudinal direction, a good display characteristic, such as brightness, is obtained. However, when the display unit is viewed in the widthwise direction, the display characteristic is considerably lowered, which causes the convenience of the cellular phone to be considerably lowered.